keepalived高可用lvs

    LVS只是作一個負載均衡，經過訪問VIP來訪問後端的網站程序，一旦LVS宕機，整個網站就訪問不了，這就出現了單點。因此要結合keepalive這種高可用軟件來保證整個網站的高可用。本文將介紹如何利用keepalive來實現LVS的高可用(以LVS的DR模式爲例，生產環境後臺的real server 網站內容是一致的，爲了看到實驗效果，這裏是兩個不一樣的頁面)。 

實驗拓撲：

1.在兩臺Real Server上配置web服務

2.配置兩臺Real Server

配置腳本以下：

#!/bin/bash
#

VIP='10.1.88.88'
NETMASK='255.255.255.255'
IFACE='lo:0'

case $1 in
start)
	echo 1 > /proc/sys/net/ipv4/conf/all/arp_ignore
	echo 1 > /proc/sys/net/ipv4/conf/lo/arp_ignore
	echo 2 > /proc/sys/net/ipv4/conf/all/arp_announce
	echo 2 > /proc/sys/net/ipv4/conf/lo/arp_announce

	ifconfig $IFACE $VIP broadcast $VIP netmask $NETMASK up
	route add -host $VIP $IFACE
	;;
stop)
	echo 0 > /proc/sys/net/ipv4/conf/all/arp_ignore
	echo 0 > /proc/sys/net/ipv4/conf/lo/arp_ignore
	echo 0 > /proc/sys/net/ipv4/conf/all/arp_announce
	echo 0 > /proc/sys/net/ipv4/conf/lo/arp_announce

	ifconfig $IFACE down
	;;
*)
	echo "Usage: $(basename $0) {start|stop}"
	exit 1
esac

3.配置keepalived

keepalived master的配置：

! Configuration File for keepalived

global_defs {
   notification_email {
       root@localhost
   }
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node1
}

vrrp_script chk_down {                #配置腳本
	script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"  #腳本內容
	interval 2     #間隔兩秒執行一次腳本
	weight -6      #若是腳本執行失敗則優先級減6
}

vrrp_instance VI_1 {               #配置實例     
    state MASTER                       #狀態
    interface eno16777736              #keepalived所配置的接口   
    virtual_router_id 88              #VRID
    priority 100                     #優先級
    advert_int 1                    
    authentication {
        auth_type PASS
        auth_pass 1111
    }

    virtual_ipaddress {
		10.1.88.88/16 dev eno16777736 label eno16777736:0    #VIP
    }

	track_script {
		chk_down
	}
	
	notify_master "/etc/keepalived/notify.sh master"
	notify_backup "/etc/keepalived/notify.sh backup"
	notify_fault  "/etc/keepalived/notify.sh fault"
}

virtual_server 10.1.88.88 80 {    #配置虛擬服務器
	delay_loop 3        
	lb_algo rr
	lb_kind DR
	protocol TCP

	sorry_server 127.0.0.1 80        #當全部realserver宕機後，則啓用sorry_server

	real_server 10.1.68.5 80 {            #realserver配置
		weight 1
		HTTP_GET {        #realserver健康狀態檢測
			url {
				path /
				status_code 200
			}

			connect_timeout 1
			nb_get_retry 3
			delay_before_retry 1
		}
	}

	real_server 10.1.68.6 80 {
		weight 1
		HTTP_GET {
			url {
				path /
				status_code 200
			}

			connect_timeout 1
			nb_get_retry 3
			delay_before_retry 1
		}
	}
}

keepalived backup配置：

global_defs {
   notification_email {
       root@localhost
   }
   notification_email_from keepalived@localhost
   smtp_server 127.0.0.1
   smtp_connect_timeout 30
   router_id node1
}

vrrp_script chk_down {
	script "[[ -f /etc/keepalived/down ]] && exit 1 || exit 0"
	interval 2
	weight -6
}

vrrp_instance VI_1 {
    state BACKUP             #配置bakup服務器state爲BACKUP
    interface eno16777736
    virtual_router_id 88
    priority 98              #優先級爲98，比master低
    advert_int 1
    authentication {
        auth_type PASS
        auth_pass 1111
    }

    virtual_ipaddress {
		10.1.88.88/16 dev eno16777736 label eno16777736:0
    }

	track_script {
		chk_down
	}

	notify_master "/etc/keepalived/notify.sh master"
	notify_backup "/etc/keepalived/notify.sh backup"
	notify_fault  "/etc/keepalived/notify.sh fault"
}

virtual_server 10.1.88.88 80 {
	delay_loop 3
	lb_algo rr
	lb_kind DR
	protocol TCP

	sorry_server 127.0.0.1 80    

	real_server 10.1.68.5 80 {
		weight 1
		HTTP_GET {
			url {
				path /
				status_code 200
			}

			connect_timeout 1
			nb_get_retry 3
			delay_before_retry 1
		}
	}

	real_server 10.1.68.6 80 {
		weight 1
		HTTP_GET {
			url {
				path /
				status_code 200
			}

			connect_timeout 1
			nb_get_retry 3
			delay_before_retry 1
		}
	}
}

在兩臺調度器上面配置httpd，用於sorry_server

在兩臺前端調度器上同時啓動keepalived

service keepalived start    #master
service keepalived start    #backup

此時兩臺調度器已經同時生成了ipvs規則

此時VIP已經在master的網卡接口上

4.測試

模擬其中一臺調度器故障，VIP當即漂移至backup調度器，不影響調度

其中有一臺故障可正常調度至另外一臺realserver

後端realserver所有故障，此時sorry_server服務器響應